1. Field of the Invention
The present invention relates to sanitary ware, such as toilet bowls, urinals, wash basins and washstands, and the production thereof so as to maintain a function which allows the easy removal of dirt over a long period of time.
2. Description of Related Art
It is essential that the surfaces of sanitary ware have good appearance and they may be cleaned for the sake of sanitation and esthetics. Moreover, It is preferable that this condition be preserved over a long period of time.
In order to maintain sanitary cleaning and good appearance, a cleanser of surfactants, acids, alkalis, and the like is typically applied to various types of scrub brushes and the surface of the sanitary ware is strongly scraped therewith. In short, dirt is removed through the force of chemical cleaning by a cleanser and the force of physical cleaning by scraping with brushes.
Unfortunately, it is hard to call this kind of cleaning work easy, so it is preferable to minimize the frequency of this work. Moreover, since it has been shown in recent years that surfactants included in wastewater contribute to environmental pollution, low amount and frequency of use thereof is preferable.
In light of such circumstances, sanitary ware have been proposed which have surf aces that are outstanding from the aspects of sanitation and good appearance.
For example, proposals have been made for methods to make it difficult for dirt to stick to sanitary ware surfaces by coating the surfaces with fluorine resins or siloxane resins having fluoroalkyl groups so as to decrease the surface energy thereof.
In addition, a method has been proposed to prevent strong adhesion of dirt to the sanitary ware surfaces by making the surfaces as smooth as possible. However, there has heretofore been insufficient study made of the relationship between surface conditions and difficulty of dirt adhesion, durability, or degree of gloss. There are only proposals for sanitary ware with flat and smooth surfaces based on conceptual awareness of good appearance and there are no proposals for the concrete means to achieve such characteristics.
The present inventors have become aware that sanitary ware, on which dirt adheres with extreme difficulty and, once it adheres, is removed with a weak flow of water, can be obtained without accompanying poor appearance by devising a structure of glazed layers.
In the embodiments of the present invention, the object is to provide sanitary ware which, without accompanying poor appearance, allows dirt to adhere with extreme difficulty and, once it adheres, to be removed with a weak flow of water.
In addition, according to the present invention, there is provided sanitary ware comprising a first coloring glaze layer formed on a ceramic body surface, a second transparent glaze layer formed on the first layer, and an engobe layer formed between the ceramic body surface and the first layer.
In the present invention, the term xe2x80x9csanitary warexe2x80x9d means an equipment used in the vicinity of rest rooms, specifically meaning toilets, urinals, strainers for urinals, toilet tanks, wash basins of wash stands, hand wash basins, etc.
xe2x80x9c50% particle diameterxe2x80x9d means the particle diameter of particles in a case where an accumulated volume of the particles from a smaller particle based on the particle distribution measurement data derived through the use of a laser diffraction method reaches to 50%.
xe2x80x9cCenterline average roughness Raxe2x80x9d is, extracting the measured length 1 from the roughness curve to the direction of the centerline thereof, making the centerline of this extracted part X axis, making the direction of the axial magnification Y axis, and expressing the roughness curve as y=f(x), the value in micrometers (xcexcm) obtained by the following equation:                     Ra        =                                            1              l                        ⁢                          ∫              0              l                                |                      f            ⁡                          (              x              )                                |                      ⅆ            x                                              [Equation  1]            
The measurement of the centerline average roughness Ra, following the definitions and notations of JIS-BO0601 (1994), was conducted by using stylus-type surface roughness measurement apparatus which is in compliance with JIS-BO651 (1996). These JIS standards, along with their English translations, can be easily obtained from Japan Industrial Standards (address: 1-24, Akasaka 4-chome, Minato-ku, Tokyo 107-0052 Japan).
A schematic diagram of this measurement apparatus is shown in FIG. 2. In the FIG. 2, a detector 11 is equipped with a stylus 12 and a skid 13, and the detector 11, into which surfaces of a sample 14 on a fixing device 15 are fed with a feeder 16, detects displacements in the vertical direction. The surface roughness curve can be obtained by displaying these displacements with a magnification device (not shown) on an indicating device or recording device.